US4188209A - Nickel-base alloy - Google Patents
Nickel-base alloy Download PDFInfo
- Publication number
- US4188209A US4188209A US05/828,718 US82871877A US4188209A US 4188209 A US4188209 A US 4188209A US 82871877 A US82871877 A US 82871877A US 4188209 A US4188209 A US 4188209A
- Authority
- US
- United States
- Prior art keywords
- weight
- nickel
- base alloy
- tungsten
- chromium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
- C22C27/06—Alloys based on chromium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
- C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
- C22C19/052—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 40%
Definitions
- This invention relates to a nickel-base alloy which is resistant to corrosion, abrasion, erosion, cavitation and to temperature cycles and possesses a high high-temperature strength.
- fittings are most likely to be damaged at their sealing surfaces. Such damage may be due to intergranular corrosion, erosion, abrasion, cavitation and/or to temperature cycles.
- the coating of the sealing surfaces of fittings with alloys by weld-surfacing has proved to be a reliable method of increasing the stability of these surfaces.
- the metal which has been applied to the sealing surfaces by weld-surfacing resist a unit pressure up to 10,000 N/cm 2 and temperature cycles up to a temperature difference of 600° C. Its Rockwell C hardness number should be 35 to 40, as a rule. Besides, structure and properties of the metal should be stable for a relatively long time and the metal should have a good workability and is required to be produced by simple technology.
- Cobalt-chromium alloys are best known as coating materials to be applied to sealing surfaces by weld-surfacing. They are distinguished by a high resistance to corrosion and erosion and have a high high-temperature strength up to 640° C. and also a high wear resistance. Their hardness decreases rapidly above 650° C. Other disadvantages reside in the high working costs and in the presence of cobalt, which results in the formation of Co 60 , which is a long-lived radioactive isotope. Besides, weld-surfacing requires preheating to a relatively high temperature, which must be maintained during the weld-surfacing. The material which has been applied is annealed and is subsequently subjected to a retarded cooling.
- nickel-chromium-boron-silicon alloys have been used more recently.
- the advantages of these alloys reside in their relatively low melting point, lower manufacturing costs and a much lower preheating temperature for weld-surfacing.
- nickel-chromium-boron-silicon alloys known from published German specifications Nos. 11 98 169 and 15 58 880 and French Pat. No. 1,376,914 are not satisfactory as regards resistance to corrosion, particularly intergranular corrosion, as well as regards high-temperature hardness and susceptibility to cracking.
- the alloy should have a hardness up to 60 on the Rockwell C scale.
- Chromium 25 to 55
- C 1 carbon content required to form carbides with refractory metals (tungsten, molybdenum)
- 0.2 a constant which is equivalent to the solubility limit of C in the nickel-chromium solid solution.
- the nickel-base alloy has the following composition in % by weight:
- Chromium 30 to 40
- Tungsten may be replaced entirely or in part by molybdenum, provided that
- the alloy may contain cobalt as an impurity up to the limit which causes the formation of the undesired Co 60 .
- the weld-surfaced coating was initially subjected to the "Strauss Test" in accordance with Stahl-Eisen Prufblatt 1975 in order to test its resistance to intergranular corrosion.
- the testing time in the boiling solution amounted to 15 hours.
- a polished section of the valve gate was subjected to metallographic examination which showed that there had been no intergranular attack on the surface of the applied layer nor at the junction between said layer and the base metal. This is apparent from the illustration in the drawing.
- valve gate was additionally exposed to the extremely aggressive fluids which contact the fittings during the decontamination and consist mainly of oxalic acid and mixed nitric and oxalic acids. In that case too, the examination of a polished section showed that there had been no intergranular corrosion and no area corrosion of metal.
- the coated valve gate was subjected to cycles consisting of heating in a furnace to about 400° C. and quenching in water. Because the tests have only a characterizing significance, they were discontinuted after 100 temperature changes. After that time, neither cracks nor other damage which could have been caused by thermal fatigue were found.
- the alloy was exposed under operating conditions to a pickling solution which was to be used in operation and was composed of 25% nitric acid of 62% concentration; 7% hydrofluoric acid of 40% concentration, balance water, at 20° C. for 0.5 hour.
- the alloy was also exposed to a pickling solution having the same composition for 24 hours. The examination of polished sections revealed no area corrosion.
- the measured hardness at room temperature amounted to 37 on the Rockwell C scale.
- the wear of the valve gate was visually inspected after 10,000 opening and closing movements. A formation of scores was not observed.
- a powder of the alloy according to the invention is particularly suitable for plasma welding and plasma spraying as well as for flame spraying and shock spraying, for gas-powder weld-surfacing and for spray welding.
- the powder is also used to make filler wire.
- Rods made of the alloy are used particularly in inert gas welding and oxyacetylene welding.
- the alloy according to the invention is used also in the manufacture of electrodes having alloy core rods and/or alloy sheaths. Strip for submereged arc welding and for spin-welding can also be made from the alloy.
- the alloy may be used to make sheet metal elements, which are applied to a base member that is to be protected.
- the material according to the invention may be cast in the manufacture of shaped members for use as machine elements which are expected to be subjected to corrosive, abrasive, erosive and/or cavitational influences.
- the alloy can also be applied to screws for separators, screws for extruders, or the like.
Abstract
The invention relates to the provision of nickel-base alloys which contain carbon, tungsten, chromium, boron, silicon, and iron. The alloys are resistent to corrosion, abrasion, erosion, cavitation and to temperature cycles and possess high high-temperature strength. They find utility particularly in thermal and nuclear power plants.
Description
This invention relates to a nickel-base alloy which is resistant to corrosion, abrasion, erosion, cavitation and to temperature cycles and possesses a high high-temperature strength.
Practice in thermal and nuclear power plants has shown that fittings are most likely to be damaged at their sealing surfaces. Such damage may be due to intergranular corrosion, erosion, abrasion, cavitation and/or to temperature cycles. The coating of the sealing surfaces of fittings with alloys by weld-surfacing has proved to be a reliable method of increasing the stability of these surfaces.
The metal which has been applied to the sealing surfaces by weld-surfacing, resist a unit pressure up to 10,000 N/cm2 and temperature cycles up to a temperature difference of 600° C. Its Rockwell C hardness number should be 35 to 40, as a rule. Besides, structure and properties of the metal should be stable for a relatively long time and the metal should have a good workability and is required to be produced by simple technology.
Cobalt-chromium alloys are best known as coating materials to be applied to sealing surfaces by weld-surfacing. They are distinguished by a high resistance to corrosion and erosion and have a high high-temperature strength up to 640° C. and also a high wear resistance. Their hardness decreases rapidly above 650° C. Other disadvantages reside in the high working costs and in the presence of cobalt, which results in the formation of Co60, which is a long-lived radioactive isotope. Besides, weld-surfacing requires preheating to a relatively high temperature, which must be maintained during the weld-surfacing. The material which has been applied is annealed and is subsequently subjected to a retarded cooling.
For these reasons, nickel-chromium-boron-silicon alloys have been used more recently. The advantages of these alloys reside in their relatively low melting point, lower manufacturing costs and a much lower preheating temperature for weld-surfacing.
On the other hand, the nickel-chromium-boron-silicon alloys known from published German specifications Nos. 11 98 169 and 15 58 880 and French Pat. No. 1,376,914 are not satisfactory as regards resistance to corrosion, particularly intergranular corrosion, as well as regards high-temperature hardness and susceptibility to cracking.
It has been stated in published German specification No. 24 46 517 that this behavior is due to the fact that said alloys have a high carbon content, which results in the formation of carbides. For this reason, the last-mentioned published German specification discloses a nickel-chromium-boron-silicon alloy which is virtually free from carbon and should contain the same only as an impurity up to 0.05%. It is hardly believable that such very low carbon content can be controlled during the production of the alloy because practice has shown that carbon is introduced together with all other components. For this reasons, the carbon content will always exceed 0.05% and these alloys in the compositions used in practice and described in the examples contain copper, which is used to oppose intergranular corrosion. On the other hand, the presence of copper decreases the weldability of the alloy.
It is an object of the invention to provide a nickel-base alloy which essentially contains carbon in order to permit a formation of carbides and which has a composition such that intergranular corrosion, erosion, abrasion, cavitation and thermal fatigue are avoided and a hardness of at least 35 on the Rockwell C scale is achieved. For extremely high stresses, the alloy should have a hardness up to 60 on the Rockwell C scale.
This object is accomplished by the provision of a nickel-base alloy having the following compostion in % by weight:
Carbon: 0.5 to 5
Tungsten: 2 to 15
Chromium: 25 to 55
Boron: 0.5 to 3.5
Silicon: 1 to 5
Iron: 1 to 5
Nickel: balance
in which
(a) % by weight C=% by weight C1 +% by weight C2 +0.2;
(b) % by weight W=36×% by weight C1 ; and
(c) % by weight Cr≧17+9×% by weight C2 =4×% by weight C
Preferably,
% by weight Cr≧25+9×% by weight C2 -4×% by weight C.
% by weight C1 =carbon content required to form carbides with refractory metals (tungsten, molybdenum)
% by weight C2 =carbon content required to form chromium carbide
0.2=a constant which is equivalent to the solubility limit of C in the nickel-chromium solid solution.
In a preferred embodiment, the nickel-base alloy has the following composition in % by weight:
Carbon: 0.5 to 3
Tungsten: 7 to 10
Chromium: 30 to 40
Boron: 0.5 to 1.5
Silicon: 1 to 3
Iron: 2 to 3
Nickel: balance
Tungsten may be replaced entirely or in part by molybdenum, provided that
% by weight Mo=18×% by weight C1.
The alloy may contain cobalt as an impurity up to the limit which causes the formation of the undesired Co60.
The invention will now be explained with reference to an example:
An alloy powder having the following preferred composition in % by weight: Carbon 1.2; chromium 31.5; silicon 2.0; boron 0.6; tungsten 7.8; iron 2.0; balance nickel; was applied by weld-surfacing in a plasma welding plant to a valve gate for use in a nuclear power plant.
The weld-surfaced coating was initially subjected to the "Strauss Test" in accordance with Stahl-Eisen Prufblatt 1975 in order to test its resistance to intergranular corrosion. The testing time in the boiling solution amounted to 15 hours. After the test, a polished section of the valve gate was subjected to metallographic examination which showed that there had been no intergranular attack on the surface of the applied layer nor at the junction between said layer and the base metal. This is apparent from the illustration in the drawing.
An additional test in accordance with MW-Prufblatt E2 of Mannesmann-Werke was conducted in a boiling solution of H2 SO4 +Fe2 (SO4)3 ×XH2 O for 8 hours. In that case, no intergranular attack was observed too.
Owing to their specific effects, these tests are intended only for wrought alloys and their significance as applied to cast alloys might be doubted. For this reason the valve gate was additionally exposed to the extremely aggressive fluids which contact the fittings during the decontamination and consist mainly of oxalic acid and mixed nitric and oxalic acids. In that case too, the examination of a polished section showed that there had been no intergranular corrosion and no area corrosion of metal.
To test its resistance to temperature cycles, the coated valve gate was subjected to cycles consisting of heating in a furnace to about 400° C. and quenching in water. Because the tests have only a characterizing significance, they were discontinuted after 100 temperature changes. After that time, neither cracks nor other damage which could have been caused by thermal fatigue were found.
To test its resistance to pickling, the alloy was exposed under operating conditions to a pickling solution which was to be used in operation and was composed of 25% nitric acid of 62% concentration; 7% hydrofluoric acid of 40% concentration, balance water, at 20° C. for 0.5 hour. The alloy was also exposed to a pickling solution having the same composition for 24 hours. The examination of polished sections revealed no area corrosion.
The measured hardness at room temperature amounted to 37 on the Rockwell C scale.
The wear of the valve gate was visually inspected after 10,000 opening and closing movements. A formation of scores was not observed.
A powder of the alloy according to the invention is particularly suitable for plasma welding and plasma spraying as well as for flame spraying and shock spraying, for gas-powder weld-surfacing and for spray welding. The powder is also used to make filler wire. Rods made of the alloy are used particularly in inert gas welding and oxyacetylene welding. The alloy according to the invention is used also in the manufacture of electrodes having alloy core rods and/or alloy sheaths. Strip for submereged arc welding and for spin-welding can also be made from the alloy. The alloy may be used to make sheet metal elements, which are applied to a base member that is to be protected.
Owing to its excellent technological properties, the material according to the invention may be cast in the manufacture of shaped members for use as machine elements which are expected to be subjected to corrosive, abrasive, erosive and/or cavitational influences. The alloy can also be applied to screws for separators, screws for extruders, or the like.
It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention.
Claims (8)
1. A nickel-base alloy which is resistant to corrosion, abrasion, erosion, cavitation and to temperature cycles and possesses a high high-temperature strenght, consisting essentially of the following composition in % by weight:
Carbon: 0.5 to 5
Tungsten: 7 to 15
Chromium: 25 to 55
Boron: 0.5 to 3.5
Silicon: 1 to 5
Iron: 1 to 5
Nickel: balance
and
(a) % by weight C=% by weight C1 +% by weight C2 +0.2;
(b) % by weight W=36×% by weight C1 ; and
(c) % by weight Cr≧17+9×% by weight C2 -4×% by weight C, % by weight C1 being the carbon content required to form carbide refractory materials and % by weight C2 being carbon content required to form chromium carbide.
2. A nickel-base alloy according to claim 1, wherein % by weight Cr≧25+9×% by weight C2 -4×% by weight C.
3. A nickel-base alloy according to claim 1, having the following composition in % by weight:
Carbon: 0.5 to 3
Tungsten: 7 to 10
Chromium: 30 to 40
Boron: 0.5 to 1.5 Silicon: 1 to 3
Iron: 2 to 3
Nickel: balance.
4. A nickel base alloy according to claim 2, having the following composition in % by weight:
Carbon: 0.5 to 3
Tungsten: 7 to 10
Chromium: 30 to 40
Boron: 0.5 to 1.5
Silicon: 1 to 3
Iron: 2 to 3
Nickel: balance.
5. A nickel-base alloy according to claim 1, having the following composition in % by weight:
Carbon: 1.2
Chromium: 31.5
Silicon: 2.0
Boron: 0.6
Tungsten: 7.8
Iron: 2.0
Nickel: balance.
6. A nickel-base alloy according to claim 2, having the following composition in % by weight:
Carbon: 1.2
Chromium: 31.5
Silicon: 2.0
Boron: 0.6
Tungsten: 7.8
Iron: 2.0
Nickel: balance.
7. A nickel-base alloy according to claim 1, characterized in that tungsten is replaced entirely or in part by molybdenum and % by weight Mo=18×% by weight C1.
8. A nickel-base alloy according to claim 2, characterized in that tungsten is replaced entirely or in part by molybdenum and % by weight Mo=18% by weight C1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2639325A DE2639325C3 (en) | 1976-09-01 | 1976-09-01 | Use of a nickel-based alloy |
| DE2639325 | 1976-09-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US4188209A true US4188209A (en) | 1980-02-12 |
Family
ID=5986891
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US05/828,718 Expired - Lifetime US4188209A (en) | 1976-09-01 | 1977-08-29 | Nickel-base alloy |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4188209A (en) |
| DE (1) | DE2639325C3 (en) |
| FR (1) | FR2371515A1 (en) |
| GB (1) | GB1588464A (en) |
| IT (1) | IT1084710B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4363659A (en) * | 1979-06-04 | 1982-12-14 | Cabot Corporation | Nickel-base alloy resistant to wear |
| US4394347A (en) * | 1981-07-09 | 1983-07-19 | Avco Corporation | Brazing filler metal composition and process |
| US4404049A (en) * | 1978-03-16 | 1983-09-13 | Fukuda Metal Foil & Powder Co., Ltd. | Hard facing nickel-base alloy |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2829702C3 (en) * | 1978-07-06 | 1982-02-18 | Metallgesellschaft Ag, 6000 Frankfurt | Nickel-based alloy |
| US4181523A (en) * | 1978-10-10 | 1980-01-01 | Bhansali Kirit J | Nickel-base wear-resistant alloy |
| JPS6059077B2 (en) * | 1980-05-02 | 1985-12-23 | 福田金属箔粉工業株式会社 | Nickel-based overlay alloy |
| JP3148340B2 (en) * | 1991-08-27 | 2001-03-19 | 福田金属箔粉工業株式会社 | High-toughness chromium-based alloy for hard facing, powder thereof, and engine valve for automobile coated with the alloy |
| DE19959378B4 (en) * | 1999-12-09 | 2005-03-03 | Mtu Aero Engines Gmbh | Coating process for magnesium alloy components |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2744009A (en) * | 1951-07-30 | 1956-05-01 | Crucible Steel Co America | Ni-cr hard facing alloys |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2219462A (en) * | 1938-03-11 | 1940-10-29 | Haynes Stellite Co | Welding rod |
-
1976
- 1976-09-01 DE DE2639325A patent/DE2639325C3/en not_active Expired
-
1977
- 1977-08-25 IT IT26929/77A patent/IT1084710B/en active
- 1977-08-29 US US05/828,718 patent/US4188209A/en not_active Expired - Lifetime
- 1977-08-29 FR FR7726198A patent/FR2371515A1/en active Granted
- 1977-08-30 GB GB36262/77A patent/GB1588464A/en not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2744009A (en) * | 1951-07-30 | 1956-05-01 | Crucible Steel Co America | Ni-cr hard facing alloys |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4404049A (en) * | 1978-03-16 | 1983-09-13 | Fukuda Metal Foil & Powder Co., Ltd. | Hard facing nickel-base alloy |
| US4363659A (en) * | 1979-06-04 | 1982-12-14 | Cabot Corporation | Nickel-base alloy resistant to wear |
| US4394347A (en) * | 1981-07-09 | 1983-07-19 | Avco Corporation | Brazing filler metal composition and process |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2639325C3 (en) | 1981-03-19 |
| IT1084710B (en) | 1985-05-28 |
| FR2371515A1 (en) | 1978-06-16 |
| FR2371515B1 (en) | 1981-07-24 |
| DE2639325B2 (en) | 1980-06-19 |
| DE2639325A1 (en) | 1978-03-02 |
| GB1588464A (en) | 1981-04-23 |
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